A major whooping cough outbreak in England and Wales escalated in July with 1,047 new cases in one month.
The total number of cases for 2012 is now 3,523, three times higher than the number for the whole of 2011. The Health Protection Agency (HPA) has said it is "very concerned" by the outbreak.
The disease, which was nearly eradicated in the UK a generation ago, is more common than at any time in the past 20 years.
Also known as pertussis, a whooping cough is a serious illness in the very young and can be fatal. Babies are offered a vaccine at two, three and four months of age. Dr Gayatri Amirthalingam, from the HPA, said: "Parents should ensure their children are vaccinated on time so they are protected at the earliest opportunity and be alert to the signs and symptoms."Reuse content